Lightning-arrester



W. B. POTTER.

- LIGHTNING ARRBSTER.

. (No Model.)

QV I xxx Patented Dec. 24, 1895;

FTELL Wrrpl ESEEE UNITED STATES PATENT OFFICE.

'WIIILIAM B. POTTER, OF SCIIENECTADY, NEIV YORK, ASSIGN OR TO THE GENERAL ELECTRIC COMPANY, OF NEIV YORK.

LlGHTNING-ARRESTER.

SPECIFICATION forming part of Letters Patent No. 551,786, dated December 24, 1895.

Application filed August 31, 1895. Serial No. 561,093. (No model.)

To aZZ whom it may concern:

Be it known that 1, WILLIAM B. POTTER, a citizen of the United States, residing at Schenectady, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Lightning-Arresters, (Case No. 266,) of which the following is a specification.

My invention relates to lightning-arresters, and has particular reference to arresters for high-potential circuits, especially for those employing alternating currents.

It has for its object to provide an arrester in which the character of the current will not affect the result and which may be capable of adaptation to any voltage by an extension of the principles involved in its construction for moderate potentials.

As ordinarily constructed, lightning-arrestcrs have been eflicacious only upon continuous-current circuits or upon alternating-current circuits of very moderate potentials. A lightning-arrester capable of working with certainty upon potentials of a thousand volts or upward has been practically unknown. This is particularly the case where an inductive load is thrown upon a circuit, in which case, where the self-induction and capacity of the circuit balance each other, a resonant condition may be brought about and the potential may rise very greatly, even to such a point as to are across the ordinary dischargespaces or spark-gaps without the intervention of the static discharge. Increasing the size of the parts does not give a corresponding protection, and in practice it has been found impossible to insure protection to lines between which exist electromotive forces of several thousand volts.

My invention therefore consists in an arrester provided with a plurality of spark-gaps arranged in series. Each of the spark-gaps is placed in an insulating-chute and is separated from the others in such a manner that it is impossible for the discharge to are across from one gap to another. In conjunction with the spark-gaps as thus arranged I provide a magnetic blow-out. The coil which I prefer for this blow-out has no iron. core. By pref erence I provide two of these coils, one upon each side of the series of chutes, and so arrange them that the lines of force are transverse to the path of the are, as particularly described in my Patent No. 543,892, issued August 6, 1895. By dispensing with the iron in the core I avoid hysteresis effects, and also prevent the backing up or impedance of the discharge, which would tend to force it from the ground-path and compel it to pass through the machine. The coil without iron is not only free from hysteresis effects, but provides a substantially uniform magnetic field, so that a number of arcs formed simultaneously at different gaps in the series will be acted upon with practically equal power. In the arrangement of circuits which I prefer the coil is connected between two of the electrodes forming the series of spark-gaps, so that it is in a shunt to the path of the are. This arrangement I have found efficacious, the amount of current flowing in the coil being ample for the purposes for which it is designed.

In installing a lightning-arrester of my design it is of course intended to place one in each line, and between each arrester and the machine which it is intended to protect I place an impedance-coil, which is ordinarily composed of a number of turns of the main or feeder in which the arrester may be placed, and by preference has no iron core.

The accompanying drawings show an embodiment of my invention in practical form, Figure 1 being a side elevation with one side removed, showing the interior construction of the arrester. Fig. 2 is a plan view partly in section. Fig. 3 is a diagram of the circuits in the arrester itself. Fig. 4 is a diagram showing the manner of installing it.

In Figs. 1 and 2 A is a base of suitable nonconducting material. B B are supports ordinarily made of metal, designed to support the side pieces C C, which are made of slate or other refractory insulating material. D D are dividing walls between the spark-gaps which are formed between the electrodes E E. By this construction it will be seen that when the two parts or side walls C C are in position the intervening septa D D form with them inclosing chutes, as in my patent before referred to, so that the arc is confined in a small space, and the lines of force from the coils act terminal N over the lead I'I, across the sparkenergetically upon it. I I are the coils, which i are formed without an iron core, as already expressed in my statement of invention. Two of these are employed, one upon each side of the arrester. Intervening blocks 0 0 enable the parts B to form a common support for the coils and the side walls of the apparatus.

The circuits will be more readily understood from Fig. 3. N is the terminal connected to line, from which the path of the current is through the coils I, connected to the second of the electrodes E by the lead II. The lead II passes from the terminal N directly to one of the electrodes. Thus the static discharge will pass directly from the gaps to the terminal G, and from there to ground. The line-current, however, will pass partly over the lead II and partly through the coils I and the lead II, energizing the coils and blowing out the are at the first air-gap. If the resistance of the series of air-gaps be not suificient to prevent it, the line-current will follow down the series, but the coils I will remain energized and will blow out the arcs as fast as they form.

Fig. at shows the arrangement of the installation. K K are the induction-coils to which I have referred, and m n the lines or mains. L A indicates the lightning-arrester connected between the mains and the ground at G. M is the machine to be protected. The lightning discharge passes along one of the lines, but penetrates with difficulty through the coil K, the self-induction of which tends to prevent the passage of the high-potential alternatinglight discharge, and the current, as it is ordinarily expressed, is backed down through the lightning-arrester to ground, the arcing across being interrupted by the magnetic field, as already explained.

By the construction which I have described I have been enabled to break arcs upon a potential of ten thousand volts with certainty and without the damaging effects so often noticed in discharges of this character. I

have also been. enabled to adjust the lightning-arrester to various potentials by employing various numbers of spark-gaps in series, and so far as my experiments have gone I believe that potentials of any amount may be broken by having a sufficient number of such gaps.

That I claim as new, and desire to secure by Letters Patent of the United States, is

1. A lightning arrester comprising a number of spark-gaps in series, each gap inclosed in a chute of refractory insulating material, and a common arc-extinguishing means for all of the spark-gaps.

2. A lightning arrester comprising a number of spark-gaps in series, each spark-gap inclosed in a chute, and a common magnetic blow-out for all of the gaps.

3. A lightning arrester comprising a number of spark-gaps in series, each spark-gap in closed in a chute, and a common magnetic blow-out for all of the spark-gaps composed of coreless coils.

1 A lightning arrester consisting of a number of spark-gaps in series, each spark-gap inclosed in a chute, and a common arc-extinguishing means for the spark-gaps, comprising coils connected between the line terminals and one of the spark-gap electrodes, forming a shunt to the path of the main discharge.

5. A lightning arrester consisting of a number of spark-gaps in series, each spark-gap inclosed in a chute, and a common arc-extinguishing means for the spark-gaps, compris ing coreless'coils connected between the line terminal and one of the spark-gap electrodes forming a shunt to the path of the main discharge.

In witness whereof I have hereunto set my hand this 27th day of August, 1895.

WILLIAM B. POTTER. \Vitnesses:

A. F. MAoDeNALo, B. 13. IIULL. 

